Monitoring the effects of pharmaceutical or radiation intervention in cancer patients is an important tool in the management of disease. Current methods for monitoring tumor response to therapy using imaging include CT and PET scanning. Emerging methods include functional and molecular imaging. In addition to the use of imaging to visually assess tumor growth, a physician may biopsy the tumor to assess the tumor response via histopathology. Mouse models are increasingly used in the study of possible cancer treatments and these same imaging/biopsy techniques are often used in mouse models. The ability to biopsy the mouse based on an imaging study and to perform repeat biopsies in the same region of the mouse would enable more accurate and repeatable mouse studies. Therefore, in the proposal we plan to develop a robotic system for biopsy and related needle procedures in mice, based on MR images. The robotic system will allow for targeting of the anatomy from our small animal MR scanner, and will include a specialized mouse holder for securing the animal. For the robotic system to be able to perform these procedures, the animal must be securely restrained in an animal holder. In addition, the area to be biopsied must be firmly held in some manner, much like the area is held by the fingers of an experienced animal technician. Therefore, we also propose to develop a new mouse holder as part of this work. The specific aims are therefore: 1. Develop a mouse holder to restrain the animal and expose the flank for biopsy and/or injection. Integrate an existing robotic needle driver with the mouse holder on the same platform. 2. Manufacture a new needle holder for the robot and develop the software to command the robot from small animal MRI images for precision needle guidance. 3. Perform a feasibility study using 10 mice to demonstrate the ability of the robot to biopsy the mouse flank as selected on the MRI images and evaluate the accuracy of the system. [unreadable] [unreadable] [unreadable]